Construction of internal-combustion engines.



' J. McKECHNIE. CONSTRUCTION, OF INTERNAL COMBUSTION ENGINES.APPLICATION FILED FEB. I2. 1916.

1 0,722 Patented Nov. 28, 1916.

. 4 SHEETSLSHEET 1.

R 4 a j 4 if f I J. McKECHNlE. CONSTRUCTION OF INTERNAL COMBUSTIONENGINES.

' APPLl( 3ATl0N FILED FEB. 12. 1916.

4 SHEETS-SHFET 2.

J. IVIcKECHNIE. CONSTRUCTION OF INTERNAL COMBUSTION ENGINES. APPLICATIONFILED FEB. 12. 1916.

4 SHEETS-SHEET 3.

0. 6' F (D/Z 7 M f j I a o J. fame Patented Nov. 28,1916.

1'. McKECHNIE.

CONSTRUCTION OF INTERNAL COMBUSIION ENGINES; APPLICATION FILED FEB. 12.-1916.

Patented Nov. 28, 1916.

4 SHEETS-SHEET 4.

UNITED STATES PATENT osnion.

JAMES MoKE C HNIE, OF IBARROW-IN-FURNESS, ENGLAND, ASSIGNOR 'IO VICKERSLIMITED, OF LONDON, ENGLAND.

' Specification of Letters Patent.

Patented Nov. 28, 1916.

Application filed February 12, 1916. Serial No. 77,937.

To all whom it may concern:

Be it known that I, JAMES MoKnonmna subject of the King of GreatBritain, residing at Naval Construction Works, Barrowin-Furness, in thecounty of Lancaster, England, have invented certain new and useful I;Improvements in the Construction of Inter nal-Combustion Engines, ofwhich the following is a specification.

This invention relates to the construction of internal combustionengines of the balanced kind employing three pistons, the central one ofwhich has an area approximately equal to the combined areas of the outerpistons and moves in an opposite direction to the latter.

My invention provides certain improvements in engines of this kind(especially two-stroke cycle engines) which allow of greater compactnessand economy in construction and increased efficiency.

The means for cooling piston rods and istons in engines of this kind isdescribed and claimed in the application of James McKechnie Ser. No.106634 filed June 29, 1916, which is a division of the presentapplication.

- end, where it joins the passage leading to the According to myinvention two compres sion spaces are provided, each comprising thespace between the outer end of one of the smaller pistons and the outerend of one of, the smaller cylinders, and also a passage between thesmaller and larger cylinders. The fuel may be sprayed through twoinjection valves without the admixture of air or the usual air sprayingdevice may be employed. The spray is directed acrossthe upper end ofeach side cylinder toward the middle of the engine. To obtain the mostefiicient combustion I may practically confine the compression space ofeach small cylinder to a transverse channel formedby channeling thepiston end and the end wall of the cylinder, the piston at theconclusion of its outer stroke almost meeting the cylinder end except atthe channel, which preferably widens from its outer or spraying end toits inner central cylinder. The central piston may serve also as an aircompressor for the supply of scavenging air, for this purpose thecentral cylinder being provided with an extension a ove the piston,forming a chamber in which the air is compressed.

In an engine of the three piston balanced used, one for each injectionvalve.

type andof large size, it is difiicult to provide efiiclent watercooling for the central piston and piston rod by ordinary methods and Ipropose to employ an improved water cooling system in which the water isintroduced and escapes through pipes or channels extending along theaxis of the piston and piston rod and passing through the piston head. I

A convenient form of valve gear for operating the two injection valvesand also the air starting valve comprises a cam shaft with a double orreversing cam for each injection valve and a double cam for, thestarting valve, the shaft being displaceable axially for forward orreverse drive. A hand wheel and screw device may be used to move the camshaft for regulating and reversing. Two fuel pumps are preferalbllly epumps may be in the same casing and driven from a pair of eccentrics ona shaft'geared to the crank shaft through reducing gear. In order thatthe invention may be clearly understood and readily carried into effect,the same will be described more fully with reference to the accompanyingdrawings, in

which I Figure 1 is a vertical section of an engine embodying thevarious features ofmy invention. Figs. 2 and 3- are elevations of the asaid engine taken at right angles to each other, with some details insection; Flg. 4;

is a section of the upper part of the central cylinder and pistonshowing a method of fitting a scavengingpump; and Fig. 5 is a verticalsection, on an enlarged scale, of the cooling arrangement. a A is theengine casing.

B is the central cylinder and C, C are the outer cylinders.

D is the large central pistonand E, E are I the smaller side pistonsworking in the opposite direction to the piston D and with a combinedcross sectional area equal to that of the central piston.

F is the crank shaft with central crank f and two side cranks fconnected respecbular piston rod 03 belonging to the piston D.Qonnecting rods 0 are provided between the S11E66 cranks f and the sidetrunk pistons G is a fixed inner tube and G an outer tube leading thecooling water through the central piston rod 03 and piston D.

H, H are a pair of double or reversing cams for the injection valves Jand H is a double cam for the starting valve K, the

cams H and H being fitted on the cam shaft h which is displaceableaxially for regulating and reversing by the hand wheel h.

L is the fuel pump casing. The central cylinder B is in opencommunication with both of the side cylinders C through the passages cand at the end of the 'compression stroke, in the position shown in Fig.1, the large piston D approaches the end of its cylinder so closely asto leave only theminimum clearance permissible. There are therefore twocompression spaces, one for each side cylinder, comprising the passagesc and a transverse channel e in the upper end of each of the pistons E;these pistons also approach closely to the cylinder ends, except for thechannels 6', which lead diametrically across the pistons from the innerpassages c to the spraying nozzles or valves situated at J at the outersides of the cylinders C. The ends of the cylinders C are suitablyformed to complete the transverse channels and to confine thecompression space at the end.

of the stroke practically to these channels and the passages c. .Inlarge engines of the present type it is of importance to be able tospray the fuel in such amanner that intimate mixture is obtainedthroughout the compression space and by separating the compression spaceinto two parts each hav- 1ng 1ts own spray and' moreover, by formmg eachcompression space as a channel along which the spray is inwardlydirected,-

the greatest efficiency of spraying and fuel combustion is obtainable.As already mentioned each channel e may V widen from the outer end,where the no zzle J is placed, to the inner end, where leads into thepassage 'c. The passage 0 is made large enough to givea free outlet tothe exhaust gases and the scavenging air, the air entering through ports6' in the small cylinders and escaping through exhaust ports I) in thelarge cylinder, on uncovering by the respective pistons C and B. Anon-return air valve K may be placed at the top of one of the outercylinders C for use in air starting and a safety valve M may be placedat the top of the other cylinder.

The casing, A is provided with the water jacket a around the centralcylinder B and the side cylinders C, the lower part of the jacket alsosurrounding the central part a of the casing, through which the tubularpiston rod d passes, so that the water jacket assists in cooling-thisrod. "As already mentioned, it is desirable to cool the thick centralpiston rod by a special water cooling device comprising the fixed innerand outer tubes G and G and extensions through the piston and pistonrod. ater is introduced by the inlet 9 through the fixed tube G thatleads through the center of the cylinder or pump cover and passes intothe end of the piston rod tube 9, which slides upon the tube G as thepiston reciprocates. The outer fixed tube G having'an outlet 9 at itsupper end surrounds the central inlet tube G, leaving an annular channelfor the outward flow of the water, this outer tube passing through astufiing box in the upper end of the piston rod (Z'.

The tube (which for convenience in fitting is made in three sections)extends from the outer end of the rod 03 to just within the piston D,which is hollow. A small collar on the upper end of the tube 9 at closesthe annular passage at the top of the,tube 5/ immediately above openingsformed in the piston rod and piston and leading to the interior of thelatter, return openings passing back from the upper part of the pistonchamber to the water channel in the rod d. The lower section 9* of thecentral tube 9 is perforated at g to allow of communication with the,annular return channel formed between the tube and the inner wall of thetubular piston rod.

The cooling water flows downwardly through the central tubes G and g tothe lower end of the piston rod 03, thence upwardly through the annularpassage surrounding the tube 9 to the openings g into the interior ofthe piston D, back through the return openings to the annular passageinside the piston rod and thence to the outlet 9 through the annularpassage between the two fixed tubes G and G. An efficient circulationthroughall parts of the piston and piston rod exposedto high temperatureis thus obtained.

The valve gear for the starting and injection valves is shown in Figs. 2and 3. As already mentioned the two double cams H and H are mounted onthe same shaft h, which can be displaced axially for regulating andreversing purposes by the Wheel k and screw k The timing valve K for airstarting, from which a" connection passes to the non-return air valve Kon one of the cylinders C, is shown in section in Fig. 2 with the valvestem meeting one element of the air valve cam H. For starting in thereverse direction the shaft It is shifted to the right to bring thesecond cam element into operation. The air supply is cut out or in bythe cut out valve K shown in section in Fig. 3 and operated by thestarting hand wheel is acting throughthe worm is and worm quadrant 74The valves K and K are operative only when the air supply is turned onby the valve K A connection Z from the quadrant k to the fuel pumpcasing L cuts 011' the fuel supply when the valve K is open, by, forexample, holding open the fuel suctionvalve.

The two double cams H for the two fuel injection valves J are shaped toadmit of timing and variable .fuel supply by axial adjustment of theshaft 72. in a manner well known. They operate the yalves simultaneouslythrough the lever connections 3' and by moving the shaft hpast thecentral dead position the cams serve for reverse drive.

It is preferredto place two fuel pumps in the pump casing L, each pumpsupplying its own injection valve J which may. be arranged to injectunder high pressure liquid fuel unmixed with air, the fuel entering thecylinder in the form of a spray. The pumps are driven through rods Z bythe half speed eccentrics Z (Fig. 1) geared to the crank. shaft Fthrough gearing Z the intermediate.

wheel of which drives the lubricating pump L through the eccentric Z(Figs. 1 and 3).

Z is the fuel inlet pipe and Z is an outlet pipe leading to an injectionvalve J.

If the central piston D is to serve-also for scavenging purposes, by 1utilizingits upper end, the construction of the cylinder B and piston Dmay be modified as shown in Fig. 4, the piston D being extended at Dthrough the cylinder and provided with a flange 0Z in the enlargedcylinder extension B, so that the flanged end of the piston D forms apump piston of increased area, sweeping out at'eachstroke a sufiicientvolume of air to serve for the scavenging air.

supply ofthe three cylinders. The extension or pump cylinder B isprovided with air inlet and outlet valves 6' and b and an air chamber 6to which the air supply pipe leading to the cylinders C is connected at6 The air inlet or supply pipe is shown at c in Fig. 3, the air passinginto the cylinders C through the inlet ports 0 (Fig. 1). alreadyreferred to. C The pump may be double acting, as shown, the under-sideof the piston flange d being utilized by placing air valves 6' and 12both at the upper and lower ends of the pump cylinder B.

Fig. 4 does not show thecooling means for-the piston rod (1', but thearrangement of tubes shown in Fig. 1 may of course be employed inconjunction with the air compressor of Fig. 4.

The general operation of an engine conf structed on the linesillustrated is similar to that of an ordinary two strokeengine withignition on Diesel lines. The method of ignition, however, forms noparts of the present invention. Starting with the engine in the positionshown in Fig. 1, the

air has already been fully compressed and is now confined to the smallspaces left inthe side cylinders C by the channels e on the top of thepistons E and the short com- 'municating channels 0 leading to thecentral cylinder B. At about .the maximum compression the cams H operatetheinjection valves J and a'fine spray of fuel is forced by the fuelpumps through the spraying nozzles into the two compression'spaces,

\ the spray being directed inwardly along the channels 6 of the pistonsE. The compression in the cylinders C is sufficient to ignite the fueland combustion'follows on the usual lines. The pressure acts equally onthe pistons D and E, which move in opposite directions but exert torqueupon the shaft F der B are uncovered by the piston D andv at about thesame point of the stroke the inlet ports 0"in the two side cylinders Care uncovered by the pistons E and scavenging air passes through theseports into both side cylinders and then through the passages 0 into thecentral cylinder B and out through the exhaust port. A clear path isthus provided between the inlet at oneend of the cylinder spaces and theexhaust at the other end. The pistons and cylinder ends are formed toinsurea good sweep for the air, the ends of the side cylinders andthetops .of the side pistons sloping slightly up to ward the center whilethe lower end of the central piston D is conical. On the inward strokeof the pistons the ports 0 and b are closed and compression of thecharge is effectied, completing the usual two-stroke cyc e. /i

What I claim and desire tosecure by Letters Patent of the United Statesis 1. In an internal combustion engine, a

large central cylinder, two side cylinders having a combined crosssection approximatelyequal to that of the large cylinder and connectedto the latter by passages, a large piston in the central cylinderadapted at the end of the compression stroke almost to meet the cylinderend so as to leave no compression space in the said cylinder, two smallside pistons acting oppositely to and balancing the pressures on thelarge piston, two separate compression spaces each made in the form of atransverse channel leading from the outside edge of a, small cylinder toone of the said passagesleading to the central cylinder, and aninjection valve at the outer end of each channel and directed inwardlytoward the central cylinder.

2. In an internal combustion engine, a large central cylinder, two sidecylinders having a combined cross section approximately equal to that ofthe large cylinder and connected to the latter by passages, a largepiston in the central cylinder adapted at the end of the compressionstroke almost to meet the cylinder end so as to leave nocompressionspace in the said cylinder, two small side pistons actingoppositely to and balancing the pressures on the large piston, atransverse channel in the end "of'each of the small pistons, eachchannel forming a narrow compression space leading from the outer edgeof the small cylinder to the passage communicating with the largecylinder, and an injection valve at the outer edge of each smallcylinder and directed along the corresponding channel.

' 3. In aninternal combustion engine, a large central cylinder, two sidecylinders having a combined cross section approximately equal to that ofthe large cylinder and connected to the latter by passages, a largepiston in the central cylinder adapted at the end of the compressionstroke almost to meet the cylinder end so as to leave no compressionspace in the said cylinder, two

small side pistons acting oppositely to and balancing the pressures onthe large piston, two separate compression spaces each made 1n the formof atransverse channel leading from the outside edge of a small cylinderto one of the said passages leading to the central cylinder, aninjection valve at the outer end of each channel and directed inwardlytoward the central cylinder, and a separate fuel pump for each valve andpump driving gear connected to the crank shaft.

4.. In an internal combustion engine, a large central cylinder providedWith eX- haust ports in its Walls, two side cylinders each provided withairinlet ports in their walls and having a combined cross sectionapproximately equal to that of the large cylinder and connected to thelatter by passages, a large piston in the central cylinder adapted atthe end of the compression stroke almost to meet the cylinder end so asto leave no compression space in the said cylinder, two small sidepistons'acting oppositely to and balancing the pressures on the largepiston, two separate compression spaces each made in the form of atransverse channel leading from the outside edge of a small cylinder toone of the said passages leading to the central cylinder, and aninjection valve at the outer end of each channeland directed inwardlytoward the central cylinder.

JAMES MGKEGHNIE.

